About one in every ten dogs experiences overreactions to allergens, placing allergies as one of the most widespread and common health problems in dogs. As it occurs with humans, genetics is the main factor why dogs suffer from allergies. Meanwhile hazardous environmental factors affect the development of their immune system, predisposing some of them to allergies. Allergic reactions always begin with a sensitizing experience, i.e. a prior encounter with an allergenic substance, which will initiate the symptoms when the next contact with the agent occurs. The allergen is the agent or substance, usually a protein, that is recognized by the body as an antigen, i.e. a potential dangerous intruder. This leads to the production of antibodies triggering an exacerbated immune response.
The immune system is like a team of different cells. Among them, the lymphocytes are capable of distinguishing whether a substance is part of the body or not. During what is called the sensitizing experience, a substance is identified as an antigen for the first time, and these cells start producing specific antibodies to counteract that antigen. Antibodies then stay in the mast cells, which are mainly located in the areas of the body that are more frequently in contact with the external environment. They are ready to attack the antigen in an eventual subsequent contact.
If the allergen comes in contact with the antibodies, an allergic reaction begins in the mast cells. This is characterized by the release of histamine and other chemicals responsible of an inflammatory response, such as irritation and other signs of allergies.
Types of Allergies
Regardless of the type of allergen and the way it accesses the body, the mechanism of the reaction is the always same. It results in one or a combination of symptoms, such as: generalized itchy rash, tearing, respiratory signs such as coughing, sneezing gasping and rhinitis as well as vomiting and diarrhea. Allergies can be severe, but they are not usually life threatening. The exception is the most serious and dangerous allergic reaction, the anaphylactic shock.
Among the most usual causes of dogs’ allergies are the substances present in the environment that can be inhaled or that can come in contact with their skin, as well as food, medicines, vaccines, exoparasites, and stress. According to the nature of the agent that prompts the immune response and the way in which it reaches the body, it is possible to distinguish different types of allergies in dogs: fleas, inhalant, contact, and food. Bacterial Hypersensitivity, also considered as a kind of allergy, takes place when bacteria, fungi and yeasts take advantage of the opportunity offered by the changes in the immune system caused by other types of allergy.
The most common allergies in dogs are in descending order: flea allergy dermatitis (FAD), atopic dermatitis, contact allergy and food allergy. The presence of allergic skin diseases in dogs is the most common cause of opportunistic bacterial infections.
Diagnosis and Treatment
Despite the differences between each type of allergy, their prevention and treatment are similar. In general, avoiding the exposure to allergens is a way to prevent allergic onset. However, this is not always easy to do.
Treatment for allergies is aimed to control skin irritation and infections, preventing these reactions from turning into more severe conditions.
Also, the treatment employed is based on the severity of the symptoms and includes topical medications, shampoos and lotions to treat or prevent irritative skin problems as well as antihistamines and corticosteroids, which are sometimes
complemented with nutritional supplements containing omega-3 and antibiotics in
the case of an infection. Your veterinary can prescribe the adequate treatment according to the type of allergy and severity of the case that you dog is suffering from.
Sometimes the diagnosis of skin allergies requires specific intra-dermal and blood tests to identify the allergen. During intradermal skin tests, which are similar those used in humans, small quantities of different allergens are injected into the dog’s skin to test its reaction to each one of the potential allergenic agents. Blood tests can be used to identify the presence of antibodies to specific allergens. Due to the high rate of false positives in blood tests, intradermal tests are usually the preferred method to use, except if it is a case of food allergies.